Multiplex immunohistochemistry is a powerful tool to visualize the spatial composition of inflammatory cells in the tumor microenvironment. Prostate cancer generally fits into the category of cancers that do not respond to immune checkpoint inhibitors. This may relate to the finding that most prostate cancers are known to be “immune cold” tumors. Nevertheless, the mechanisms leading to this immune desert-like state are not fully understood. We have designed a multiplex immunohistochemistry T cell panel to begin to systematically investigate the adaptive immune response in prostate cancer. We implemented an iterative chromogenic IHC assay approach, in which whole pathology slides are subjected to IHC and then scanned. Coverslips are removed and slides are then subjected to dissolution of the chromogen, antibody removal, second round antibody staining and rescanning. Iteratively stained whole slides scans are color deconvoluted and fused into a single multiplex image in HALO®. For analysis, we trained the Random Forest Tissue Classifier to define the stromal and epithelial components of the tumor separately, and used the HighplexFL module of HALO to quantify the densities of eight T cell phenotypes in the tumor epithelial and stromal subcompartments. Loss of PTEN is associated with the development of aggressive and metastatic prostate cancer. One of the mechanisms by which PTEN is postulated to drive disease aggressiveness is via immune suppression. Therefore, we used this panel to explore the association between the PTEN status of the tumor and the T cell densities in the tumor microenvironment, by comparing matched regions of tumors that showed PTEN genomic alterations and those with intact PTEN, within the tumor nodule.